Physically the dizzy will fit and most of the internals are the same. What
may be different are the advance weights and plates. The vacuum advance will
be different also.
Of course you can use the internals from a 2L dizzy and try to get a vacuum
unit or run w/o one as the Solex cars do.
FWIW, the advance plate in Roadster dizzies goes bad quickly and becomes
very notchy. Very poor design as the balls are too small and the metal too
soft.
Mike